Diagnosing system for reductant dosing system

An SCR system may include a controller configured to diagnose errors with a dosing system. The controller may control a pump to compensate for a loss in pressure when dosing reductant and may maintain the pressure as close to a target pressure by modifying a parameter affecting the operation of the pump. The modification of the parameter may be used to determine an estimated flow feedback. The controller may use the estimated flow feedback data and commanded dosing amount data to calculate a percentage error in response to and using an integrated commanded flow and an integrated estimated flow feedback to detect errors of the dosing system. The errors may include an injector stuck closed error, a blocked pressure line error, a partial blockage of a pressure line or injector error, an injector stuck open error, a disconnected pressure line error, a leakage of a pressure line or injector error.